A standard vehicle door latch has latch parts, at least one locking lever, at least one drive and a linkage between an actuating lever subassembly and the latch parts as well as a quick blocking element.
In motor vehicle door latches of this type, typically the drive moves the locking lever, which is normally configured as a central locking lever, to the locked or unlocked positions. Furthermore, in principle also further positions of the locking lever can be achieved, for example such as the so-called antitheft position.
The unlocking process is generally achieved with a keyless entry systems. These systems allow a vehicle user to carry an identification device, for example a code card, which initiates a dialog with a control system provided in the vehicle when the vehicle user approaches the vehicle or actuates the outside door actuating element, that is the door handle. During the course of this dialog, access authorization of the vehicle user seeking access is verified. Once the authorization has been verified, the control system sends a signal to at least one or all of the door latches of the motor vehicle. Then, the motor vehicle door latch is unlocked with the help of its drive and can then be opened mechanically, for example with the help of the outside door handle.
The problem with this is that a vehicle user seeking access has already operated the outside door handle while the dialog is still in process or before the associated motor vehicle door latch has assumed the unlocked position. The reason for this is that the above-mentioned keyless entry systems require a certain response time to carry out the unlocking operation. This response time includes an activation interval in order to activate the system as the vehicle user approaches, an authorization verification interval and finally the actual action interval.
In practice, response times of about 100 msec or more are known, which are perceived by the vehicle users as too long compared to conventional motor vehicle door latch systems. Furthermore, it is possible that the vehicle user has already operated the outside door handle in an attempt to open it before the associated motor-vehicle door latch has assumed the unlocked position. The vehicle user then has to release the outside door handle and perform another confirmation step, which is considered a clear limitation in terms of convenience.
For this reason, quick-unlock systems have been developed that use quick-unlock elements. They all share the basic principle of bridging or shortening the comparatively long unlocking path of the locking lever and/or central locking lever in that the quick-unlock element allows the mechanical opening of the associated motor vehicle door latch practically immediately following actuation of the drive.
In particular, German 102 47 842 of Brose provides that shifting of the central locking arrangement from the locked to the unlocked state initially effects a movement of the linkage and/or linkage arrangement from the locked into the unlocked state and thereafter a movement of the inside blocking element from the locked to the unlocked state. For this purpose, a quick-unlock lever is provided, the locking lever and the quick-unlock lever being moved to the unlocked and locked states by means of the drive. The quick-unlock lever is coupled to the linkage arrangement, specifically via a linkage rod. The known configuration has proven useful in principle, however it has an overall uninviting design because the quick-unlock lever is mounted on the locking lever and/or both pivot about the same axis of rotation.
A similar system is seen in EP 1 288 408 of Scholz. This system offers a further development in that the quick-unlock lever releases the latch parts during the course of the quick-unlock operation with the help of the drive, substantially independently of the position of the locking lever. The quick-unlock lever is configured as a one-arm lever that is pivoted on the locking lever. In the system of U.S. Pat. No. 6,737,758 of Weyerstall, s the quick-unlock element can be connected to the lock mechanism and/or a blocking element in a more or less integral manner. Within the framework of an alternative, the quick-unlock element can be configured as a spring snap element, which is released by the drive and snaps into its actuation position under spring force.